Downhole tools with independently-operated cutters and methods of milling long sections of a casing therewith

Abstract

In one aspect, an apparatus for use in a wellbore is disclosed that in one non-limiting embodiment includes a plurality of cutters, each cutter having expandable cutting elements, a control unit associated with each cutter to expand the cutting elements of its associated cutter and a controller that controls each of the control units to independently activate and deactivate each cutter in the plurality of cutters to expand the cutting elements of each such cutter.

The invention claimed is: 
     
       1. A method of milling a casing in a wellbore, comprising:
 conveying a tool inside the casing, the tool including a plurality of cutters configured to mill the casing; 
 locating a first cutter in the plurality of the cutters at a first location in the casing; 
 activating the first cutter to engage with the casing at the first location; 
 milling the casing with the first cutter to a second location and deactivating the first cutter; 
 positioning a second cutter in the plurality of cutters at the second location; 
 activating the second cutter to engage with the casing at the second location; 
 milling the casing with the second cutter to a third location; and 
 determining a physical condition of at least one of the first cutter and the second cutter utilizing information about a measured inner dimension of the casing above the at least one of the first cutter and the second cutter while such cutter is milling the casing and deactivating such cutter when the physical condition of such cutter is below a desired condition. 
 
     
     
       2. The method of  claim 1  further comprising determining in real time an inner dimension of the wellbore above one of the first cutter and the second cutter while such cutter is milling the casing. 
     
     
       3. The method of  claim 2 , wherein determining the inner dimension comprises using a device selected from a group consisting of: a tactile caliper; and an acoustic device. 
     
     
       4. The method of  claim 1 , wherein the tool further includes a spear configured to engage with the casing to pull the casing from the hole, wherein the method further comprises:
 engaging the spear with the casing above the milled casing and pulling the tool to pull the casing out of the wellbore. 
 
     
     
       5. The method of  claim 1  further comprising providing a two-way communication between the tool and a surface location by one of: mud pulse telemetry; and electromagnetic telemetry. 
     
     
       6. A method of milling a casing in a wellbore, comprising:
 conveying a tool inside the casing, the tool including a plurality of cutters configured to mill the casing; 
 locating a first cutter in the plurality of the cutters at a first location in the casing; 
 activating the first cutter to engage with the casing at the first location; 
 milling the casing with the first cutter to a second location and deactivating the first cutter; 
 positioning a second cutter in the plurality of cutters at the second location; 
 activating the second cutter to engage with the casing at the second location; and milling the casing with the second cutter to a third location, wherein activating one of the first cutter and the second cutter includes using a controller to control a control device associated with the one of the first cutter and the second cutter, the control device including a motor that drives a pump to supply a fluid under pressure to expand cutting elements of the one of the first cutter and the second cutter. 
 
     
     
       7. The method of  claim 6 , wherein the controller is located at one of: in the tool; at the surface; and partially in the tool and partially at the surface. 
     
     
       8. An apparatus for use in a wellbore, comprising:
 a plurality of cutters, each cutter having expandable cutting elements; 
 a control unit associated with each cutter to expand the cutting elements of its associated cutter; 
 a controller that controls each control unit to independently activate and deactivate each cutter in the plurality of cutters to expand the cutting elements of each such cutter; and 
 a device that provides measurements relating to an inner dimension of the wellbore above at least one of the cutters in the plurality of cutters, wherein the controller determines a physical condition of at least one of the cutters in the plurality of cutters from measurements of an inner dimension in the wellbore while such cutter is milling an element in the wellbore. 
 
     
     
       9. The apparatus of  claim 8 , wherein the device that provides measurements of the inner dimension of the wellbore is selected from a group consisting of: a caliper; and an acoustic device. 
     
     
       10. The apparatus of  claim 8  further comprising a spear configured to engage with a fish in the wellbore to pull the fish out of the wellbore. 
     
     
       11. The apparatus of  claim 8  further comprising a telemetry system that provides two-way communication between a tool carrying the cutters while the tool is in the wellbore and surface location. 
     
     
       12. The apparatus of  claim 11 , wherein the telemetry system provides the two-way communication via one of: mud pulse telemetry; and electromagnetic telemetry. 
     
     
       13. An apparatus for use in a wellbore, comprising:
 a plurality of cutters, each cutter having expandable cutting elements; 
 a control unit associated with each cutter to expand the cutting elements of its associated cutter; and 
 a controller that controls each control unit to independently activate and deactivate each cutter in the plurality of cutters to expand the cutting elements of each such cutter, wherein each control unit includes a motor that drives a pump to supply a fluid under pressure to expand the cutting elements of its associated cutting elements. 
 
     
     
       14. The apparatus of  claim 13 , wherein the controller is located at one of: in a tool that contains the cutters; at a surface location; and both at the surface location and in the tool. 
     
     
       15. The apparatus of  claim 14  further comprising one or more sensors that provide information about a parameter of interest relating to a physical condition of a tool carrying the plurality of cutters while a cutter in the plurality of cutters is performing a cutting operation. 
     
     
       16. The apparatus of  claim 15 , wherein the controller determines the physical condition of the tool from the information provided by the one or more sensors and in response thereto controls the operation of at least one cutter.